DISEASES OF CULTIVATED PLANTS 659 



The better and quicker way of making up Bordeaux mixture 

 by the barrel consists in placing the two half-barrel tubs on an ele- 

 vated platform and then, by means of hose or spigots, allowing the 

 two solutions to flow together into a barrel. 



Straining the Materials. No matter what quantity of mixture 

 is to be made up, it is necessary to strain the materials through a 

 wire strainer. The best type of strainer is made of brass wire, with 

 18 or 20 meshes to the inch. If all the copper solution is strained 

 and then the milk of lime is strained into the dilution vessels, it 

 will not be necessary to strain the Bordeaux mixture as, on account 

 of its flocculent character, it is sometimes more difficult to pass 

 through the strainer than the lime milk. Some very good strainers 

 made of copper are on the market and may be obtained from the 

 makers of spray pumps. One of the best, which can be made at 

 home, is in the form of a 'box about a foot square, the bottom of 

 which is a rather heavy board (preferably of hardwood) with a hole 

 bored through it, into which a piece of gas pipe l 1 /^ to 2 inches in 

 diameter and 8 to 12 inches long is fitted. The box is of course open 

 at the top. Fitting just inside this box is a second and lighter box, 

 also open at the top, and having an overhanging strip nailed around 

 the top which supports it. The bottom of this inner box should be 

 made so as to slope at an agle of about 30, and should be made of 

 wire screen. The slanting bottom makes it harder to clog with the 

 spray, and the inner box, being movable, can be inverted and washed 

 in a tub of water. 



Method of Preparing Bordeaux Mixture for Large Operations. 

 In large operations stock solutions should always be used, as the 

 time required to dissolve the material is saved. 



Stock Solutions. These can be prepared of both the copper sul- 

 phate and the lime. They may be made by dissolving copper sul- 

 phate in water at the rate of 1 pound per gallon, and lime in the same 

 ratio, although a strength twice as great may be used in warm 

 weather. When stock solutions are on hand it is only necessary to 

 measure off the required quantity of each and dilute with water be- 

 fore mixing. In preparing a stock solution of copper sulphate, a 50- 

 gallon barrel may be filled about two-thirds or three-fourths full of 

 water ; then a sack, or a box with perforations over which copper wire 

 has been tacked, containing 50 pounds of bluestone, should be sus- 

 pended in the upper part of the barrel and enough water added to 

 fill the barrel. In from twenty-four to thirty-six hours this material 

 will be entirely in solution, and the sack or box may be removed. A 

 slight stirring will insure the even distribution of the bluestone, after 

 which the solution is ready for use. 



The copper sulphate should be measured in a copper or granite- 

 ware receptacle, iron or tin vessels being quickly destroyed by either 

 copper sulphate or Bordeaux mixture. 



Use of an Elevated Platform. If possible the dilution tanks 

 should be raised so high on an elevated platform that the mixture 

 can be conducted by gravity directly into the spray tank beneath. 

 If a hillside is available, it is much the most convenient place to do 



